From bccd2f3d588996195eb3533e8a4230effc6f9f81 Mon Sep 17 00:00:00 2001
From: Jan <jsteemann@users.noreply.github.com>
Date: Fri, 29 Mar 2019 09:23:34 +0100
Subject: [PATCH] acquire mutex when serializing conductor state (#8620)

---
 arangod/Pregel/Conductor.cpp | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/arangod/Pregel/Conductor.cpp b/arangod/Pregel/Conductor.cpp
index c3826d8dcb..2d4903f99e 100644
--- a/arangod/Pregel/Conductor.cpp
+++ b/arangod/Pregel/Conductor.cpp
@@ -687,16 +687,15 @@ void Conductor::collectAQLResults(VPackBuilder& outBuilder) {
 }
 
 VPackBuilder Conductor::toVelocyPack() const {
+  MUTEX_LOCKER(guard, _callbackMutex);
+
   VPackBuilder result;
   result.openObject();
   result.add("state", VPackValue(pregel::ExecutionStateNames[_state]));
   result.add("gss", VPackValue(_globalSuperstep));
   result.add("totalRuntime", VPackValue(totalRuntimeSecs()));
   _aggregators->serializeValues(result);
-  {
-    MUTEX_LOCKER(guard, _callbackMutex);
-    _statistics.serializeValues(result);
-  }
+  _statistics.serializeValues(result);
   if (_state != ExecutionState::RUNNING) {
     result.add("vertexCount", VPackValue(_totalVerticesCount));
     result.add("edgeCount", VPackValue(_totalEdgesCount));